This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Our lab focuses on studying neck injuries that produce chronic pain, and part of this research has recently incorporated imaging studies of ligaments in the spine. We believe that changes to the fiber microstructure may be an important component in producing chronic pain following injury. Previously, we have used polarized light to observe the changes in collagen fiber microstructure as the ligament is stretched, simulating a whiplash injury. This technique is based on transmission of light through the tissue, requiring destructive sample preparation. We believe that surface-based methods, like second harmonic generation, would be a good next step for our injury model. We would like to develop polarization-sensitive second harmonic generation imaging and utilize the birefringence of the collagen network, which will allow us to observe changes to the network following injurious loading. While we are still in preliminary stages, if this technology provides relevant data, it may prove an important part of our injury model, linking fiber kinematics to other mechanical and neurologic pain markers.